Court will not allow child custody to a third party who is a stranger. The court can allow the child custody to a person other than parents if he is related to the child with blood or affinity.
Parents are the natural guardian of child. But mother gets priority over the father if the child’s age is below five years. In absence of parents the grandparents can take custody of child.
A person who is a complete stranger to the child cannot get his custody. It would be harmful for the welfare of that child. The court is the supreme custodian in respect of minor children. Hence, it is the paramount duty of the court to consider the welfare of the child while granting his custody.
Currently the child is happy with her family. So the court will not permit her custody because there is no reason to disturb the cosy ambience. You have to prove the reasons for leaving the present custody. The chances are very bleak to get custody of that child.